۱۳۹۱ آذر ۸, چهارشنبه

Ashfall from the Karymsky Volcano




The Karymsky stratovolcano stands 1,536 meters (5,039 feet) above sea level, and most of its eruptions and occasional lava flows originate from the summit. Karymsky is the most active of Kamchatka’s eastern volcanoes, with almost constant (on a geologic time scale) volcanism occurring since at least the late 18th century, when the historical record for the region began.
Because of the high levels of volcanic activity on the Kamchatka Peninsula, the Kamchatka Volcanic Eruption Response Team (KVERT) monitors the activity levels of several volcanoes and issues updates including aviation alerts and webcams. KVERT reported moderate seismic activity at Karymsky between November 2–9, 2012. Such activity can indicate the movement of magma beneath or within a volcanic structure and that an eruption may be imminent. The Tokyo Volcanic Ash Advisory Center (VAAC) subsequently reported an explosive eruption at Karymsky on November 9 at 22:15 Universal Time.
This astronaut photograph of the resulting ash plume was taken approximately 1 hour and 35 minutes after the eruption began. The plume extends from the summit of Karymsky to the southeast, with brown ash deposits darkening the snow cover below the plume.
The Akademia Nauk caldera—now filled with water to form the present-day Karymsky Lake—is located to the south of Karymsky volcano. Calderas are formed by explosive eruption and emptying of a volcano’s magma chamber, leading to collapse of the structure to form a crater-like depression. Akademia Nauk last erupted in 1996.
Astronaut photograph ISS033-E-19822 was acquired on November 9, 2012, with a Nikon D3S digital camera using an 800 millimeter lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 33 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by William L. Stefanov, Jacobs/ESCG at NASA-JSC.
Instrument: 
ISS - Digital Camera

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